Mixing apparatus and method



19965 J. w. WATSON 3,203,674

MIXING APPARATUS AND METHOD Filed Sept. 24, 1962 2 Sheets-Sheet 1 IN VENTOR. James VIZ/111a:- Watscrn Aug. 31, 1965 J. w. WATSON MIXINGAPPARATUS AND METHOD 2 Sheets-Sheet 2 Filed Sept. 24, 1962 INVENTOR.James SA/[Hist Wafis an United States Patent Office 3,203,674 PatentedAug. 31, 1965- 3,203,674 MIXIYG APPARATUS AND lVIETHGI) James W. Watson,Lansing, Ill., assignor to Swift & Company, Chicago, Ill, a corporationof Illinois Filed Sept. 24, 1962, Ser. No. 225,570 14 Claims. (Cl.259-3) This invention relates to an improved method and apparatus forthe batch mixing of materials. More particularly, this invention relatesto a method for mixing or granulating material in a rotary drum mixerand for discharging the material therefrom; and to an improved rotarydrum mixer having an improved discharge device.

In the past, rotary drum mixers have generally consisted of a rotatabledrum having an opening in the center of one end for introducingmaterials to be processed and an opening in the center of the other endfor discharging the processed material. A door is generally located atthe discharge end for closing the opening when filling and mixing. Aseries of longitudinal flights are generally located within the drum.These flights pick up material from the bottom of the drum and showerthe material from the top of the drum as it rotates. To effect thedischarge, the door is removed from the discharge end of the drum and achute is inserted through the center opening. This chute intercepts theshowering material and diverts it through the opening to the outside ofthe drum.

Where it is desired to roll the materials along a smooth surface to mixand agglomerate them as in granulation, the flights have been found tointerfere with the desired rolling action. Many attempts have been madeto modify the conventional rotary mixer to overcome this problem. Thesemodifications usually consist in some manner of shortening the height ofthe flights. By such modifications, an attempt is made at achieving arolling bed such as is found in a continuous granulator. However, sincethe flights are only partially removed, the rolling bed falls short ofthat found in a continuous granulator and thus granulation is onlypartially affected. Further, the alteration of the flights slows thespeed of discharge since the material must still be raised and showeredonto a chute for discharge through a center opening. These shorterflights carry less material, and hence must make more revolutions inorder to discharge the same amount of material as conventional flights.

It is therefore an object of this invention to provide an improvedgranulator.

Another object of this invention is to provide an improved rotary drummixer having a continuous, uninterrupted interior wall.

Another object of this invention is to provide an improved dischargedevice for a rotary drum mixer.

Another object of this invention is to provide an improved method forgranulating material in a rotary drum.

Still another object of this invention is to provide an improved methodof discharging material from a rotating granulator.

Other objects and advantages will become apparent from the followingdescription and drawings.

Briefly, my invention comprises sealing one end of a rotatablecylindrical zone, introducing material into the zone, rotating the zone,and opening an annular area about the periphery of said one end of thezone to allow a selected amount of said material to pass out of the zonethrough said annular opening. This method may be implemented by a hollowcylindrical means having a continuous uninterrupted inner surface, a'means connected to said cylindrical means for imparting rotary motionthereto, and closing means connected to one end of said cylindricalmeans, said closing means being adapt ed to completely seal' the end ofthe cylindrical means during mixing .and to open an annular area aboutthe periphery of the end of said cylindrical means for dischargingmaterial therethrough. The system may be used with either batch type orcontinuous type operations by regulating the size of the annular openingand the amount of time which it is open. The closing means preferablyis, in effect, an expandable door and comprises an expandable closuremeans mounted between.the discharge end of the cylindrical means and anend member spaced therefrom. The expandable means is preferably aninflatable tube, mounted in such a manner that when the tube isinflated, it will fill the space between the discharge end of thecylindrical means and the end member. Whenthe tube is deflated, itcontracts leaving an annular spacebetween the discharge end of thecylindrical means and'the end member.

While my invention may be eflectively used for various purposes, ithasbeen found to be particularly effective in granulating'plant food offertilizer. In this process the lower end of iacylindrical zone issealed and the zone is rotated. Solids and liquids are introduced intothe interior of the zonelthrough an opening in the center of the higherend. After the solids and liquids have remained in therot'ating zone fora suflicient period to form granules, or to receive any other desiredtreatment, an annular area is opened about the periphery of' the lower'end of thev'zone, and the treated material is allowed to pass out ofthe rotating zone through the am nular opening.

It is readily apparent that the method of discharging through an annularopening, which may be sealed by an inflatable tube or similar device,has the unique advan-. tages of: 1) providing a rolling bed such aswould be found in a continuous. granulator, (2) allowing the bed to betreated with various liquids, (3) allowing the agglomeration ofmaterialto form granules without the detrimental interference of flights, and(4) allowing the granules to flow rapidly out of the mixer by naturalmeans as the mixer rotates.

Further objects and advantages of my invention may be more fullyunderstood from the following description and drawings wherein:

FIGURE 1 is a side elevation, in a vertical section, of a preferredembodiment of my invention with the' discharging means in the openposition.

FIGURE 2 is a side elevation, in vertical section, of a portion of thesame embodiment showing the closing means 'in closed position. i

FIGURE? 'is an end elevation taken along line 3-3 of FIGURE 1.

FIGURE 4 is a side elevation in vertical section of a portion of amodification of the device shown in FIG- URE 1. V

FIGURE 5 is a side elevation in vertical section of a portion of anothermodificationof the device shown in FIGURE 1.

FIGURE 6 is a side elevation in vertical section of a portion of stillanother modification of the device shown in FIGURE 1. I

The present method will be better explained through a description of thestructure and operation of apparatus by which it is practiced. It willbecome apparent that all forms of the apparatus include a rotatabledrum, an end member spaced from the drum, and an expandable annularmeans located between the drum and end member.

Referring to FIGURES 1, 2 and 3, the preferred apparatus is acylindrical drum 10 having an inclined longitudinal axis and tracks 12about the periphery thereof. The tracks 12 ride on-rollers 14 whichsupport the drum and allow it to rotate about its longitudinal axis. Aring gear 16 is attached to the periphery of the drum 10 and is engagedby a pinion 18 mounted on the output shaft of a power source 20. Whenthe power source 20 is energized, pinion 18 is revolved causing ringgear 16, and hence drum 10, to rotate. A central opening 22 is providedin the higher end of drum 10 for the introduction of materials. Theopening is centrally located and small enough to prevent material withinthe rotating drum from discharging therethrough.

A hopper 48 is located directly beneath the opposite, and lower,discharge end of drum 10 to receive the material therefrom. Asubstantially circular rim 24 is mounted in the center of the dischargeend of the drum 10 by means of a plurality of brackets 26 which arerigidly attached to the outer wall of the drum 10 and to the outer sideof the rim 24. Securely mounted about the periphery of the rim 24 is aninflatable annular tube 28 having an internal air chamber 30. Astem 32,extending from the inflatable tube 28, connects the air chamber 30 witha radial tube 34 mounted internally of rim 24. Tube 34 leads to ajunction 30 located in the center of rim 24. An air line 38 is journaledthrough an air-sealed bearing 40 into the junction 36. The air line 38is bifurcated and connected through valves 42 and 44 shownillustratively, in FIGURE .1, respectively to sources of air underpressure and vacuum (notshown).

As described, the drum has an inclined longitudinal axis to aid indischarging its contents by gravity; however, the slope is not essentialto the operation of the apparatus. Also, it will be readily apparentthat in many applications a connection to a source of vacuum will not benecessary since the nature of the inflatable tube will be to return toits uninflated posture upon disconnecting the pressure source.Obviously, deflating tube 28 tends to decrease the outside diameter of adischarge end, formed by rim 24 and tube 28, of the cylindrical zoneformed generally by drum 10.

FIGURES 4, 5 and 6 represent further embodiments of the apparatus shownin FIGURES l, 2 and 3. Details of the connection of the inflatable meansto sources of air under pressure and vacuum have been omitted in theinterest of clarity. However, it will be apparent that such connectionsmay be similar to that shown in FIGURE 1, or otherwise within theknowledge of a person skilled in the mechanical .arts.

Referring to FIGURE 4, an annular tube support, or channel, 52 isformedin, or otherwise attached to, the periphery of one end of a drum10'. An inflatable annular tube 54, which is adapted to expand inwardlyof the drum, is mounted in the tube support 52. A circular end plate 56,of a diameterless than the drum 10', having an outer flange 58 isconcentrically held within the tube support by means of brackets in sucha manner that the outer flange of the end plate is spaced a short radialdistance inwardly of the tube support 52 and tube 54. Thus an annularopening is provided between the flange 58 of the circular end plate 56and the inward surface of tube 54, when the latter is deflated. When thetube 54 is inflated, it expands inwardly contacting flange 58 sealingthe end of drum 10'.

Referring to FIGURE 5, an annular tube support 62 is mountedconcentrically on the outer surface and end of a drum 10". A circularend plate 64, approximately equal to support 62 in diameter, is rigidlyconnected to the tube support by means of brackets 66 and is spaced ashort longitudinal distance from the end of drum 10". An inflatableannular tube 68, which is adapted to expand laterally against thecircular end plate 64, is mounted within the support 62. The spacebetween the tube 68, when deflated, and the inside wall of circular endplate 64 provides an annular opening 70 through which processed materialmay pass. When tube 68 is inflated,

it expands laterally contacting the inside wall of circular end plate 64and closes the end of drum 10".

The modification shown in FIGURE 6 is essentially a reversal of parts ofthe apparatus of FIGURE 5.

Referring to FIGURE 6, a circular end plate 72, having an annular tubesupport 74 mounted about its periphery, is concentrically positionedadjacent the end of the wall of drum 10" by brackets 76. The tubesupport 74 is located between end plate 72 and an end of drum 10". Anannular flange 78 is secured about the outer circumference of that endof drum 10" spaced directly opposite the tube support 74. An annularinflatable tube 80, which is adapted to expand laterally into contactwith flange 78 to close the end of drum 10", is mounted within the tubesupport 74. The space existing between the flange 78 and the tube 80,when deflated, provides an annular opening 82 through which material maybe discharged from the drum.

Operation of the apparatus of FIGURES 1-3 is illustrative. The drum ischarged with materials to be processed after first causing the annulartube 28 to be inflated to close the space between the rim 24 and the endof drum 10. Rotation of the drum is commenced, either before, during, orfollowing the charging step by energizing the motor 20 to turn pinion 18and cause ring gear 16, and hence drum 10, to revolve. This revolvingmotion is also imparted to the end member, namely, rim 24, which isrigidly secured to the drum. The pressure of the contact between thedrum wall and the inflatable tube is suflicient to effectively seal theend of drum 10 against escape of the materials therein. The material isallowed to remain in the revolving drum until it has received thedesired treatment. When the treatment is complete, the annular tube isdeflated by connecting it to the atmosphere or by closing valve 42 andopening valve 44 to positively withdraw the air from air chamber 30.Upon deflation, an annular opening is exposed at the end of the drum 10and the treated material will discharge therethrough by gravity androtation.

It is clear that many modifications and variations of the invention ashereinbefore set forth may be made without departing from its spirit andscope, and therefore only such limitations should be imposed as areindicated in the appended claims.

I claim:

1. An improved method of discharging material from a rotatablecylindrical zone comprising: rotating the cylindrical zone and openingan annular area about the periphery of one end of the rotatingcylindrical zone by decreasing the outside diameter of said end of saidzone to allow the material to be discharged through said annular area.

2. An improved method for processing material in a rotating cylindricalzone comprising: sealing one end of the rotating cylindrical zone;introducing material into the cylindrical zone; and decreasing theoutside diameter of said end thereby opening an annular area about theperiphery of said one end of the rotating cylindrical zone to allow aselected amount of the material to pass therethrough.

3. An improved method for treating material in a rotatable cylindricalzone comprising: closing one end of the cylindrical zone; introducingthe material into the zone through an opening in the center of the otherend of the zone; rotating the zone; allowing the material to remain inthe rotating zone for a sufficient period of time to accomplish thedesired treatment; opening an annular area about the periphery of thesealed end of the zone by decreasing the outside diameter of said end;and discharging a selected amount of the processed material from thezone through the annular opening while rotating said zone.

4. An improved method for granulating plant food materials comprising:introducing the materials into a closed cylindrical zone; rotating saidcylindrical zone about its longitudinal axis to mix and agglomerate thematerials; decreasing the outside diameter of one end of said zone tocreate an annular opening about the periphery of said zone at one endthereof; and discharging the mixed materials through said opening whilerotating said zone.

5. An improved rotary mixing device comprising: a hollow cylindricalmeans; means connected to said cylindrical means for imparting rotarymotion about the longitudinal axis thereof; and closing means connectedto one end of said drum, said closing means being adapted to expand toseal said end of the cylindrical zone dur ing mixing and to contract toopen an annular area about the periphery of said end of said cylindricalzone for discharging material therethrough.

6. An improved rotary drum mixed comprising a cylindrical means havingan inclined longitudinal axis; means connected to said cylindrical meansfor imparting rotary motion about said axis; means located at the higherend of said cylindrical means for allowing the introduction of materialsto the interior of said cylindrical means; and closing means located atthe lower end of said cylindrical means, said closing means beingadapted to expand to seal said lower end of said cylindrical means andto contract to provide an annular discharge area about the periphery ofsaid lower end of said cylindrical means.

7. An improved rotary drum mixer comprising a rotatable cylindrical drumhaving a charging end and a discharge end; an end member spaced adjacentthe discharge end of said drum; an annular expandable closure meanspositioned between said discharge end of said drum and said end member,said closure means filling the space between said drum and said endmember only when expanded; and means to expand and contract said closuremeans.

8. An improved rotary drum mixer comprising a rotatable cylindrical drumhaving a charging end and a discharge end; a substantially circular endmember spaced adjacent the discharge end of said drum, said end memberbeing connected to said drum at spaced locations so as to be rotatabletherewith; an annular expandable closure means mounted on one of saiddrum and said end member in opposition to the other positioned betweensaid discharge end of said drum and said end member, said closure meansfilling the space between said drum and said end member only whenexpanded, and means to expand and contract said closure means.

9. An improved plant food mixer comprising: a cylindrical drum having asmooth continuous uninterrupted inner wall; means connected to said drumfor imparting rotary motion thereto; means located at one end of saiddrum for allowing the introduction of materials to be treated and forpreventing their discharge therethrough; and closing means located atthe other end of said drum, said closing means comprising a rim mountedin the center of said other end of said drum, an annular inflatablemeans disposed about the perimeter of said rim and adjacent to saidinner wall of said drum, said inflatable means being spaced from thesaid inner wall of said drum when deflated and in contact with saidinside wall of said drum when inflated; and means operatively connectedto said tube for inflating and deflating such inflatable means.

10. An improved discharge device for a rotary drum mixer comprising: anexpandable door mounted in the discharge end of the drum, saidexpandable door being adapted to expand to seal the end of the drum andto contract to provide an annular discharge area about the periphery ofsaid end of said drum.

11. An improved discharge device for a rotary drum mixer comprising: arim mounted in the center of one end of the drum; an inflatable annulartube disposed about the perimeter of said rim and adjacent to the insidewall of the drum, said inflatable tube 'being spaced from the insidewall of the drum when deflated and in contact with the inside of thewall of said drum when inflated; and means operatively connected to saidtube for inflating and deflating said tube.

12. An improved discharge device for a rotary drum mixer comprising: atube support mounted concentrically on the outer surface of one end ofthe drum; a circular end plate connected to the drum and spaced a shortlateral distance therefrom; an inflatable annular tube mounted withinsaid tube support and adjacent to said end plate, said inflatable tubebeing spaced from the end plate when deflated and in contact with saidend plate when inflated; and means operatively connected to said tubefor inflating and deflating said tube.

13. An improved discharge device for a rotary drum mixer comprising: anannular tube support mounted on one end of the drum; a circular endplate concentrically mounted on the tube support with the outer edge ofsaid end plate being spaced a short radial distance inwardly of the tubesupport; an inflatable annular tube mounted within said tube support andadjacent said outer edge of said end plate, said tube being spaced fromthe outer edge of said end plate when deflated and in contact with saidend plate when inflated; and means operatively connected to said tubefor inflating and deflating said tube.

14. An improved discharge device for a rotary drum mixer comprising: acircular end plate mounted adjacent the end of the drum; an annular tubesupport mounted on said end plate between the end plate and the end ofthe drum; an inflatable annular tube mounted in said tube support andadjacent the end of said drum, said tube being spaced from the end ofsaid drum when deflated and in contact with the end of the wall of saiddrum when inflated; and means operatively connected to said tube forinflating and deflating said tube.

References Cited by the Examiner UNITED STATES PATENTS 539,568 5/95Bride 277-34 X 849,732 4/07 Flora 259-171 1,074,388 9/ 13 Stedman259-175 1,379,586 5/21 Faber 259-175 1,834,988 12/31 White 277-34 X2,497,736 2/50 Muller 259-175 3,038,488 6/62 Welch et al. 277-34 X3,042,360 7/62 Sneddon 198-65 X FOREIGN PATENTS 1,054,798 4/59 Germany.

CHARLES A. WILLMUTH, Primary Examiner.

1. AN IMPROVED METHOD OF DISCHARGING MATERIAL FROM A ROTATABLECYLINDRICAL ZONE COMPRISING: ROTATING THE CYLINDRICAL ZONE AND OPENINGAN ANNULAR AREA ABOUT THE PERIPHERY OF ONE END OF THE ROTATINGCYLINDRICAL ZONE BY DECREASING THE OUTSIDE DIAMETER OF SAID END OF SAIDZONE TO ALLOW THE MATERIAL TO BE DISCHARGED THROUGH SAID ANNULAR AREA.